Lamarck’s Genera of Shells. 305 
the sides ; only one cardinal tooth on each valve, sometimes 
only on one valve. 
The psammoteee are merely degenerated psammobiz, dif-. 
fering from them in having only one cardinal tooth on the 
left valve ; or sometimes one valve has no teeth, and the other 
two. They have not the form of the solenes, and their beaks are 
prominent. The ligament is external, attached to slightly pro- 
jecting nymphe, and the anterior side is destitute’ of the irre- 
gular fold of the telline. 
Type. Psammotea donacina *. 
Shell ovate, sub-depressed ; whitish, with remote red rays 5 
transverse striz small, very elegant. European Ocean? 8 
Species. PI. v. Fig. 45. 
N. Tettrnaria. (7 Genera.) 
The nymphacea tellinaria are very slightly, or not at all 
gaping at the lateral extremities, and scarcely ever have more 
than two cardinal teeth on the same valve. The ligament of 
the valves is external, but sometimes more or less buried, and, 
if the borders of the scutcheont be very near together, it ap- 
pears internal. The shells inhabit the sands, near the coasts. 
The following five genera have, besides the sometimes almost 
effaced cardinal teeth, one or two lateral teeth; the sixth and 
seventh (capsze and crassine) have none. 
1. Tellina ¢. 
Shell transverse or orbicular, in general flattened ; anterior 
side angular, with a flexuous and irregular fold on the margin. 
One or two cardinal teeth on the same valve. Two lateral 
teeth, often distant. 
The tellinze are readily known by the flexuous fold near the 
short side, on their superior margin; almost all of them have 
also lateral teeth; which are flattened on one valve. They are 
marine shore shells, slightly, or not at all gaping at the sides, 
* Allied to the donax. Lamarck’s Sthspecies, His type is P. violacea. 
+ Ecusson, the central part of the corselet. 
$ Tellina, the original latin name. 
Vox; XIV. * 
